This project investigates the degradation of factor VIII procoagulant (VIII:C) and factor VIII:C coagulant antigens (VIII:C Ag) by serine proteases and characterizes the degradation products in terms of size, using both procoagulant assays and radioimmunoassays. The nonfunctional hemophilic VIII:C from crossreacting material positive (CRM+) hemophiliacs will be similarly studied to see if any differences from normal can be found.